THE SENSE OF SMEEE IN FISHES. 
45 
reasonably sound, and it certainly holds in the case of fishes much as it does with human 
beings, for these animals respond through their olfactory organs to solutions too dilute 
to affect their gustatory organs, and the nature of the response to olfactory stimulation 
(seeking food, etc.) is such that the olfactory organs in these fishes can be called appro- 
priately distance receptors. We, therefore, believe that the fishes, although water- 
inhabiting animals, possess olfactory organs that are as much organs of smell as are 
the olfactory organs of the air-breathing vertebrates. 
SUMMARY. 
1 . A current of water passes through the nasal chambers of many fishes in a direction 
from anterior to posterior. It may be produced by ciliary action (Ameiurus) , by pres- 
sure due to the action of the respiratory muscles (Fundulus), or it may be a part of the 
true respiratory current (Musielus). 
2. By means of this current dissolved substances in the water are brought into 
contact with the olfactory surfaces. 
3. Fishes distinguish packets containing hidden food from similar packets without 
food. 
4. This power of distinguishing the two classes of packets is lost when the olfactory 
tracts are cut, when the anterior olfactory apertures are stitched up or when the aper- 
tures are plugged with cotton wool. It is revived on reopening the apertures by taking 
out the stitches or removing the cotton wool. 
Mustelus and Ameiurus discover their food chiefly through the olfactory sense; 
Fundulus uses the eyes in addition to the olfactory organs for this purpose. 
6. Mustelus, Fundulus, and Ameiuriis use the olfactory organs to scent food much 
as land animals do; these organs are true organs of smell, i. e., distance receptors for 
the chemical sense. 
POSTSCRIPT. 
Since the preparation of this paper, confirmatory results have been obtained by 
Copeland (1912) on Spheroides, and our attention has been called to the earlier papers 
by Baglioni (1909, 1910) on Balistes, etc., in which, however, the reactions of the fishes 
are assumed, rather than proved, to be dependent upon the sense of smell. 
literature cited. 
Aronsohn, E. 
1884. Beitrage zur Physiologic des Geruchs. Archiv fiir Anatomie tuid Physiologic, physiolo- 
gische Abtheilung, Jahrg. 1884, p. 163-167. 
60289° — Bull. 32 — 14 4 
